# NOT — One's Complement Negation

## Description

Performs a bitwise NOT operation (each 1 is set to 0, and each 0 is set to 1) on the destination operand and stores the result in the
destination operand location. The destination operand can be a register or a memory location.

## Instruction

| Opcode        | Assembly   | Op/En | Modern Mode | Legacy Mode | Description                                                                 |
|---------------|------------|-------|-------------|-------------|-----------------------------------------------------------------------------|
| F6 /2         | NOT r/m8   | M     | Valid       | Valid       | Reverse each bit of r/m8.                                                   |
| REX + F6 /2   | NOT r/m8*  | M     | Valid       | N.E.        | Reverse each bit of r/m8.                                                   |
| F7 /2         | NOT r/m16  | M     | Valid       | Valid       | Reverse each bit of r/m16.                                                  |
| F7 /2         | NOT r/m32  | M     | Valid       | Valid       | Reverse each bit of r/m32.                                                  |
| REX.W + F7 /2 | NOT r/m64  | M     | Valid       | N.E.        | Reverse each bit of r/m64.                                                  |

- In 64-bit mode, r/m8 can not be encoded to access the following byte registers if a REX prefix is used: AH, BH, CH, DH.

## Information

This instruction can be used with a LOCK prefix to allow the instruction to be executed atomically.

In 64-bit mode, the instruction’s default operation size is 32 bits. Using a REX prefix in the form of REX.R permits access to additional
registers (R8-R15). Using a REX prefix in the form of REX.W promotes operation to 64 bits. See the summary chart at the beginning of this
section for encoding data and limits.